1. Field of the Invention
This invention relates to a color or black-and-white type light and heat sensitive recording material to which green laser light, red laser light, or infrared laser light is applied.
2. Description of the Related Art
Various dry-type image forming methods have been studied, in which a liquid developer and the like are not used without waste problems. Among these, a method using a photocurable composition has attracted attention. This method is characterized in that a photocurable composition contained in a recording material is cured by exposure to light to form a latent image. A component concerned with color formation or color extinction is transferred within the recording material when heated and forms a color image corresponding to the latent image. The above sensitive recording material is exposed to light passed through an original image. The exposed portion is photo-cured to form a latent image. Then the recording material is heated and the uncured portion concerned with color formation or color extinction transferred to form a visible image. A perfect dry system free of waste products can be realized with this method.
There are, specifically, many types of recording materials used in this method. These recording materials are useful in methods for recording white-and-black images and are particularly useful for a color recording material. Specific examples of recording materials include recording materials disclosed in Japanese Patent Application Laid-Open (JP-A) No. 52-89915. This recording material is produced by arranging two components of a two component-type heat sensitive and color forming recording material, such as an electron accepting compound and an electron donating colorless dye, separating on the inside and outside or on both sides of a microcapsule containing a photocurable composition. When using this recording material, however, even if the photocurable composition in the capsule is sufficiently cured, the color formation of the cured portion can be insufficiently inhibited causing slight coloration of a non-image section which tends to impair contrast.
Preferred recording materials free of non-image portion coloring are typified by a recording material disclosed in JP-A No. 61-123838 in which a layer containing a photopolymerizable composition consisting of a vinyl monomer having an acid group and a photoinitiator, a separating layer, and a layer composed of an electron donating colorless dye are laminated. In this recording material, there is no coloring of the non-image sections because heat diffusion of the acid group of the portion hardened by the colorless dye or the photo-polymer section is negligible. However, coloring density is slightly low. A method of preparing a negative image in the same manner as the above method is disclosed, for example, in JP-A No. 60-119552. In this method, a recording material in which a photopolymerizable composition composed of a monomer or prepolymer for bleaching a coloring material and a photoinitiator is arranged so that it is isolated from a coloring material bleached by the monomer or prepolymer is used. This recording material, however, has the same drawback as that of the above recording material.
The present inventors have proposed a preferable recording material in JP-A Nos. 3-87827 and 4-211252, which overcomes the problems of the coloring of the non-image portion and low image density. The recording material disclosed in JP-A No. 3-87827 has a structure in which one component of a two component-type heat sensitive and color emissive recording material is contained in a capsule and the other component which is either used as a curable component of a photocurable composite or combined with a photocurable composite is arranged outside the capsule. The recording material disclosed in JP-A No. 4-211252 comprises forming, by application, a layer including a photocurable composite containing an electron accepting compound, a polymerizable vinyl monomer, and a photoinitiator, which are all disposed outside a microcapsule, and the microcapsule containing an electron donating colorless dye.
For color recording using these sensitive recording materials, it is possible to use a recording material formed of several sensitive layers each having sensitivity to different wave-lengths and producing different colors. As more preferable examples of multicolor recording materials, the above recording material proposed by the present inventors may be given. Such a multicolor recording material is specifically a multicolor recording medium represented by a structure in which a plurality of sensitive layers which are sensitized by light of different wave lengths and form colors of different hues is provided. The sensitive layers are structured so that two or more layers are laminated upward on a support member from the side of an exposing light source to the side of the support member so that the first sensitive layer sensitized by light of a center wave length of .lambda.1, an intermediate layer absorbing the light of a center wave length of .lambda.1, a second sensitive layer sensitized by light of a center wave length of .lambda.2 and emits light of a wave length different from that emitted from the first sensitive layer, . . . , an intermediate layer absorbing light of a center wave length .lambda.i-1, and a (i)th sensitive layer sensitized by light of a center wave length of .lambda.i and emits light of a wave length different from those emitted from the first layer to the (i-1)th sensitive layer are sequentially laminated. In this case, these wave lengths satisfy the relation: .lambda.1&lt;.lambda.2&lt;. . . &lt;.lambda.i, wherein i is an integer of 2 or more.
These recording materials have various uses. However, in these uses, only UV light or short wave visible light is adopted and a compact and inexpensive infrared laser and light of the green to red range cannot be adopted.